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Abstract:

A current collector for an electrochemical cell includes a member having
an outer member and an inner member coupled to the outer member by a
plurality of flexible arms configured to allow the inner member to move
relative to the outer member.

Claims:

1. A battery comprising: a housing; a cell element disposed within the
housing; a vent member coupled to the housing; and a current collector,
comprising: an inner member coupled to the vent member; an outer member
coupled to the cell element; and a plurality of flexible arms extending
between the inner member and the outer member and configured to allow the
inner member to move in a direction relative to the outer member, wherein
the direction comprises both an axial component along an axis of the
current collector and a circumferential component about the axis.

2. The battery of claim 1, wherein a portion of the plurality of flexible
arms is welded to the cell element, defining a first weld line, the inner
member is welded to the vent member, defining a second weld line, and
wherein the first and second weld lines skew when the inner member moves
in the direction.

3. The battery of claim 1, wherein at least one arm of the plurality of
arms increases in width from the inner member toward the outer member.

4. The battery of claim 1, wherein the plurality of flexible arms are
rotationally symmetric.

5. The battery of claim 4, wherein the plurality of flexible arms
comprise a degree of rotational symmetry in a range of 90 degrees to 180
degrees.

6. The battery of claim 1, wherein each arm of the plurality of arms is
substantially arcuate from the inner member toward the outer member.

7. The battery of claim 6, wherein each arm has a spiral shape about the
inner member.

8. The battery of claim 1, wherein the vent member is coupled to a bottom
portion of the housing.

9. The battery of claim 1, wherein the vent member is coupled to a lid or
cover portion of a housing.

10. The battery of claim 1, wherein a perimeter of the outer member is
substantially the same as a perimeter of a top or bottom face of the
housing.

11. The battery of claim 1, wherein the vent member includes at least one
fracture groove configured to separate from the vent member from the
housing when the vent member deploys to enable the release of gases
and/or effluent from the battery cell.

12. The battery of claim 11, wherein the at least one fracture groove is
an annular fracture groove having a V-shaped bottom.

13. A current collector for a battery cell, comprising: a first member
configured to be coupled to a cell element of the battery cell; and a
second member that is coupled to the first member, wherein the second
member is configured to be coupled to a vent member of the battery cell,
and wherein the second member is configured to move away from the first
member and to twist relative to the first member when the vent member of
the battery cell deploys.

14. The current collector of claim 13, wherein the first member is an
inner member of the current collector, and wherein the second member is
an outer member of the current collector.

15. The current collector of claim 14, wherein the first member is an
outer member of the current collector, and wherein the second member is
an inner member of the current collector.

16. The current collector of claim 14, comprising a plurality of arms
that is coupled to both the first member and the second member, wherein
the plurality of arms define a plurality of slots between the first
member, the second member, and the plurality of arms.

17. The current collector of claim 16, wherein the plurality of slots is
configured to expand when the vent member of the battery cell deploys to
allow the passage of gases and/or effluent out of the battery cell.

18. The current collector of claim 14, wherein the current collector is a
positive current collector made from copper or copper alloy.

19. The current collector of claim 14, wherein the current collector is a
negative current collector made from aluminum or aluminum alloy.

20. The current collector of claim 14, wherein the current collector has
a thickness of between approximately 1 millimeter (mm) and 2 mm.

21. A method, comprising: deploying a vent member of a battery cell
during operation, wherein the vent member is coupled to an inner member
of a current collector; and displacing the inner member of the current
collector relative to an outer member of the current collector as the
vent member deploys, wherein displacing comprises axial displacement
along an axis and a rotational displacement about the axis.

22. The method of claim 21, comprising expanding one or more apertures
disposed between the inner member and the outer member of the current
collector as the vent member deploys to faciliate a release of gases
and/or effluent from of the battery cell.

23. The method of claim 21, wherein deploying the vent member comprises
detaching the vent member from a housing of the battery cell along a
fracture groove to facilitate a release of gases and/or effluent from the
battery cell.

24. The method of claim 23, wherein detaching the vent member from a
housing of the battery cell along a fracture groove comprises separating
the vent member from the housing once a pressure inside the battery cell
reaches a predetermined amount.

25. The method of claim 21, wherein deploying the vent member comprises
bending a plurality of arms of the current collector extending between
the inner member and the outer member to enable the axial and rotational
displacement of the inner member as the vent member deploys.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. patent application Ser.
No. 13/571,183, filed. Aug. 9, 2012, which is a continuation of U.S.
patent application Ser. No. 13/087,277, filed Apr. 14, 2011, which is a
continuation of International Patent Application No. PCT/US2009/065365,
filed Nov. 20, 2009, which claims the benefit of and priority to U.S.
Provisional Patent Application No. 61/116,993, filed Nov. 21, 2008 and
U.S. Provisional Patent Application No. 61/172,148, filed Apr. 23, 2009.
The entire disclosures of U.S. patent application Ser. Nos. 13/571,183
and 13/087,277, International Patent Application No. PCT/US2009/065365,
U.S. Provisional Patent Application No. 61/116,993, and U.S. Provisional
Patent Application Nos. 61/116,993 and 61/172,148 are incorporated herein
by reference in their entireties for all purposes.

BACKGROUND

[0002] The present application relates generally to the field of batteries
and battery systems. More specifically, the present application relates
to batteries and battery systems that may be used in vehicle applications
to provide at least a portion of the motive power for the vehicle.

[0003] Vehicles using electric power for all or a portion of their motive
power (e.g., electric vehicles (EVs), hybrid electric vehicles (HEVs),
plug-in hybrid electric vehicles (PHEVs), and the like, collectively
referred to as "electric vehicles" (xEVs)) may provide a number of
advantages as compared to more traditional gas-powered vehicles using
internal combustion engines. For example, electric vehicles may produce
fewer undesirable emission products and may exhibit greater fuel
efficiency as compared to vehicles using internal combustion engines
(and, in some cases, such vehicles may eliminate the use of gasoline
entirely, as is the case of certain types of PHEVs).

[0004] As electric vehicle technology continues to evolve, there is a need
to provide improved power sources (e.g., battery systems or modules) for
such vehicles. For example, it is desirable to increase the distance that
such vehicles may travel without the need to recharge the batteries. It
is also desirable to improve the performance of such batteries and to
reduce the cost associated with the battery systems.

[0005] One area of improvement that continues to develop is in the area of
battery chemistry. Early electric vehicle systems employed
nickel-metal-hydride (NiMH) batteries as a propulsion source. Over time,
different additives and modifications have improved the performance,
reliability, and utility of NiMH batteries.

[0006] More recently, manufacturers have begun to develop lithium-ion
batteries that may be used in electric vehicles. There are several
advantages associated with using lithium-ion batteries for vehicle
applications. For example, lithium-ion batteries have a higher charge
density and specific power than NiMH batteries. Stated another way,
lithium-ion batteries may be smaller than NiMH batteries while storing
the same amount of charge, which may allow for weight and space savings
in the electric vehicle (or, alternatively, this feature may allow
manufacturers to provide a greater amount of power for the vehicle
without increasing the weight of the vehicle or the space taken up by the
battery system).

[0007] It is generally known that lithium-ion batteries perform
differently than NiMH batteries and may present design and engineering
challenges that differ from those presented with NiMH battery technology.
For example, lithium-ion batteries may be more susceptible to variations
in battery temperature than comparable NiMH batteries, and thus systems
may be used to regulate the temperatures of the lithium-ion batteries
during vehicle operation. The manufacture of lithium-ion batteries also
presents challenges unique to this battery chemistry, and new methods and
systems are being developed to address such challenges.

[0008] It would be desirable to provide an improved battery module and/or
system for use in electric vehicles that addresses one or more challenges
associated with NiMH and/or lithium-ion battery systems used in such
vehicles. It also would be desirable to provide a battery module and/or
system that includes any one or more of the advantageous features that
will be apparent from a review of the present disclosure.

SUMMARY

[0009] One exemplary embodiment relates to a current collector for an
electrochemical cell including a member having an outer member and an
inner member coupled to the outer member by a plurality of flexible arms
configured to allow the inner member to move relative to the outer
member.

[0010] Another exemplary embodiment relates to flexible current collector
for an electrochemical cell. The current collector includes an outer
portion, and inner portion, and a plurality of connecting members. Each
of the connecting members has a first end coupled to the outer portion
and a second end coupled to the inner portion. The connecting members are
configured to allow the inner portion to move relative to the outer
portion.

[0011] Another exemplary embodiment relates to an electrochemical cell
including a current collector including a member having an outer member
and an inner member coupled to the outer member by a plurality of
flexible arms configured to allow the inner member to move relative to
the outer member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a perspective view of a vehicle including a battery
module according to an exemplary embodiment.

[0013] FIG. 2 is a cutaway schematic view of a vehicle including a battery
module according to an exemplary embodiment.

[0014] FIG. 3 is a perspective view of an electrochemical cell according
to an exemplary embodiment.

[0015] FIG. 4 is a partial cross-sectional view of the electrochemical
cell shown in FIG. 3 taken along line 4-4 in FIG. 3.

[0016] FIG. 5 is a partial cross-sectional view of electrodes and
separators for an electrochemical cell according to an exemplary
embodiment.

[0017] FIG. 6 is a perspective view of a cell element provided in the form
of a jelly roll configuration according to an exemplary embodiment.

[0018] FIG. 7 is a cross-sectional view of the cell element shown in FIG.
6 taken along line 7-7 in FIG. 6.

[0019] FIG. 8 is a top view of a current collector coupled to a cell
element according to an exemplary embodiment.

[0020] FIG. 9 is an exploded perspective view of the current collector and
cell element shown in FIG. 8.

[0021] FIG. 9A is a perspective view of the current collector shown in
FIG. 9 coupled to the cell element shown in FIG. 9 with a tab of the
current collector having been folded according to an exemplary
embodiment.

[0022] FIG. 10 is a perspective view of a current collector according to
another exemplary embodiment.

[0023] FIG. 11 is a top view of the current collector shown in FIG. 10.

[0024] FIG. 12 is a top view of the current collector shown in FIG. 10
shown coupled to a cell element according to an exemplary embodiment.

[0025] FIG. 12A is an exploded side view of the current collector and cell
element shown in FIG. 12 according to an exemplary embodiment.

[0026] FIG. 12B is an exploded side view of the current collector and cell
element shown in FIG. 12 according to another exemplary embodiment.

[0027] FIG. 13A is a partial cross-sectional schematic view of the current
collector and cell element shown in FIG. 12B with a tab of the current
collector having been folded according to an exemplary embodiment.

[0028] FIG. 13B is a partial cross-sectional schematic view of the current
collector shown in FIG. 13A coupled to the cell element shown in FIG. 13A
according to an exemplary embodiment.

[0029] FIG. 14 is a top view of a current collector according to another
exemplary embodiment.

[0030] FIG. 15 is a cross-sectional view of the current collector shown in
FIG. 14 taken along lines 15-15 in FIG. 14.

[0031] FIG. 16 is a side view of the current collector shown in FIG. 14.

[0032] FIG. 17 is a perspective view of the current collector shown in
FIG. 14 being coupled to a cell element according to an exemplary
embodiment.

[0033] FIG. 18A is a partial cross-sectional schematic view of the current
collector and cell element shown in FIG. 17 taken along line 18-18 in
FIG. 17.

[0034] FIG. 18B is a partial cross-sectional schematic view of the current
collector shown in FIG. 18A coupled to the cell element shown in FIG. 18A
according to an exemplary embodiment.

[0035] FIG. 19 is a perspective view of a current collector coupled to a
cell element according to another exemplary embodiment.

[0036] FIG. 19A is a top view of the current collector shown in FIG. 19.

[0037] FIG. 20 is a perspective view of a current collector coupled to a
cell element according to another exemplary embodiment.

[0038] FIG. 20A is a top view of the current collector shown in FIG. 20.

[0039] FIG. 21 is a perspective view of a current collector coupled to a
cell element according to another exemplary embodiment.

[0040] FIGS. 22-23 are perspective views of current collectors according
to other exemplary embodiments.

[0041] FIG. 24A is a partial cross-sectional view of a cell having a
flexible current collector according to an exemplary embodiment.

[0042] FIG. 24B is a partial cross-sectional view of the cell having a
flexible current collector shown in FIG. 24A after a vent has been
deployed according to an exemplary embodiment.

[0043] FIG. 24C is a perspective view of the flexible current collector
shown in FIG. 24B according to an exemplary embodiment.

[0044] FIG. 24D is a perspective view of a housing for the electrochemical
cell shown in FIG. 24 according to another exemplary embodiment.

[0045] FIGS. 25-27 are various perspective views of a current collector
according to another exemplary embodiment.

[0046] FIG. 28 is a perspective view of the current collector shown in
FIGS. 25-27 provided in an electrochemical cell according to an exemplary
embodiment.

[0047] FIG. 29 is a cross-sectional view of the electrochemical cell shown
in FIG. 28 taken along lines 29-29 in FIG. 28.

[0048] FIG. 30 is a flow diagram of a method of manufacturing an
electrochemical cell according to an exemplary embodiment.

DETAILED DESCRIPTION

[0049] FIG. 1 is a perspective view of a vehicle 10 in the form of an
automobile (e.g., a car) having a battery system 20 for providing all or
a portion of the motive power for the vehicle 10. Such a vehicle 10 can
be an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in
hybrid electric vehicle (PHEV), or other type of vehicle using electric
power for propulsion (collectively referred to as "electric vehicles").

[0050] Although the vehicle 10 is illustrated as a car in FIG. 1, the type
of vehicle may differ according to other exemplary embodiments, all of
which are intended to fall within the scope of the present disclosure.
For example, the vehicle 10 may be a truck, bus, industrial vehicle,
motorcycle, recreational vehicle, boat, or any other type of vehicle that
may benefit from the use of electric power for all or a portion of its
propulsion power.

[0051] Although the battery system 20 is illustrated in FIG. 1 as being
positioned in the trunk or rear of the vehicle, according to other
exemplary embodiments, the location of the battery system 20 may differ.
For example, the position of the battery system 20 may be selected based
on the available space within a vehicle, the desired weight balance of
the vehicle, the location of other components used with the battery
system 20 (e.g., battery management systems, vents or cooling devices,
etc.), and a variety of other considerations.

[0052] FIG. 2 illustrates a cutaway schematic view of a vehicle 11
provided in the form of an HEV according to an exemplary embodiment. A
battery system 21 is provided toward the rear of the vehicle 11 proximate
a fuel tank 12 (the battery system 21 may be provided immediately
adjacent the fuel tank 12 or may be provided in a separate compartment in
the rear of the vehicle 11 (e.g., a trunk) or may be provided elsewhere
in the vehicle 11). An internal combustion engine 14 is provided for
times when the vehicle 11 utilizes gasoline power to propel the vehicle
11. An electric motor 16, a power split device 17, and a generator 18 are
also provided as part of the vehicle drive system.

[0053] Such a vehicle 11 may be powered or driven by just the battery
system 21, by just the engine 14, or by both the battery system 21 and
the engine 14. It should be noted that other types of vehicles and
configurations for the vehicle drive system may be used according to
other exemplary embodiments, and that the schematic illustration of FIG.
2 should not be considered to limit the scope of the subject matter
described in the present application.

[0054] According to various exemplary embodiments, the size, shape, and
location of the battery system 21, the type of vehicle 11, the type of
vehicle technology (e.g., EV, HEV, PHEV, etc.), and the battery
chemistry, among other features, may differ from those shown or
described.

[0055] According to an exemplary embodiment, the battery system 21
includes a plurality of electrochemical batteries or cells. The battery
system 21 may also include features or components for connecting the
electrochemical cells to each other and/or to other components of the
vehicle electrical system, and also for regulating the electrochemical
cells and other features of the battery system 21. For example, the
battery system 21 may include features that are responsible for
monitoring and controlling the electrical performance of the battery
system 21, managing the thermal behavior of the battery system 21,
containment and/or routing of effluent (e.g., gases that may be vented
from an electrochemical cell through a vent), and other aspects of the
battery system 21.

[0056] Referring now to FIG. 3, an isometric view of an electrochemical
cell 24 is shown according to an exemplary embodiment. A battery system
(such as battery system 20, 21) includes a plurality of such
electrochemical cells 24 (e.g., lithium-ion cells, nickel-metal-hydride
cells, lithium polymer cells, etc., or other types of electrochemical
cells now known or hereafter developed). According to an exemplary
embodiment, the electrochemical cells 24 are generally cylindrical
lithium-ion cells configured to store an electrical charge. According to
other exemplary embodiments, the cells 24 could have other physical
configurations (e.g., oval, prismatic, polygonal, etc.). The capacity,
size, design, terminal configuration, and other features of the cells 24
may also differ from those shown according to other exemplary
embodiments.

[0057] FIG. 4 is a partial cross-sectional view of a cell 24 such as that
shown in FIG. 3 taken along line 4-4 in FIG. 3. According to an exemplary
embodiment, the cell 24 includes a container or housing 25, a cap or
cover 42, a bottom portion (not shown), and a cell element 30. According
to an exemplary embodiment, the housing 25 may be constructed from a
conductive material such as a metal (e.g., aluminum or an aluminum alloy,
copper or a copper alloy, etc.). According to an exemplary embodiment,
the cell element 30 is a wound cell element. According to another
exemplary embodiment, the cell element 30 may be a prismatic or oval cell
element.

[0058] According to an exemplary embodiment, the cell element 30 includes
at least one cathode or positive electrode 36, at least one anode or
negative electrode 38, and one or more separators 32, 34. The separators
32, 34 are provided intermediate or between the positive and negative
electrodes 36, 38 to electrically isolate the electrodes 36, 38 from each
other. According to an exemplary embodiment, the cell 24 includes an
electrolyte (not shown). According to an exemplary embodiment, the
electrolyte is provided in the housing 25 of the cell 24 through a fill
hole 41. After completion of filling the cell 24 with electrolyte, a fill
plug (e.g., such as fill plug 43 as shown in FIGS. 28 and 29) may be
provided in the fill hole 41 to seal the electrolyte inside the cell 24.

[0059] The cell 24 also includes a negative current collector 40 and a
positive current collector (not shown). The negative current collector 40
and the positive current collector are conductive members that are used
to couple the electrodes 36, 38 of the cell element 30 to the terminals
26, 28 of the cell 24. For example, the negative current collector 40
couples the negative electrode 38 to the negative terminal 28 (via a tab
44) and the positive current collector couples the positive electrode 36
to the positive terminal 26 of the cell 24 (e.g., via the housing 25).
According to the exemplary embodiment shown in FIG. 4, the tab 44 of the
negative current collector 40 has been at least partially folded or bent
back over itself at least one time before being coupled to the negative
terminal 28. According to an exemplary embodiment, the current collectors
are coupled to the electrodes with a welding operation (e.g., a laser
welding operation).

[0060] According to an exemplary embodiment, the cell element 30 has a
wound configuration in which the electrodes 36, 38 and separators 32, 34
are wound around a member or element provided in the form of a tube or
mandrel 50. Such a configuration may be referred to alternatively as a
jelly roll configuration. Although the mandrel 50 is shown as being
provided as having a generally cylindrical shape, according to other
exemplary embodiments, the mandrel 50 may have a different configuration
(e.g., it may have an oval or rectangular cross-sectional shape, etc.).
It is noted that the cell element 30, although shown as having a
generally cylindrical shape, may also have a different configuration
(e.g., it may have an oval, prismatic, rectangular, or other desired
cross-sectional shape).

[0061] According to another exemplary embodiment, the electrochemical cell
24 may be a prismatic cell having prismatic or stacked cell elements (not
shown). In such an embodiment, the positive and negative electrodes 36,
38 are provided as plates that are stacked upon one another in an
alternating fashion, with the separators 32, 34 provided intermediate or
between the positive and negative electrodes 36, 38 to electrically
isolate the electrodes 36, 38 from each other.

[0062] According to an exemplary embodiment, the positive electrode 36 is
offset from the negative electrode 38 in the axial direction as shown in
the partial cross-sectional view shown in FIG. 5. Accordingly, at a first
end of the cell element 30, the wound positive electrode 36 will extend
further than the negative electrode 38, and at a second (opposite) end of
the cell element 30, the negative electrode 38 will extend further than
the positive electrode 36.

[0063] One advantageous feature of such a configuration is that current
collectors may be connected to a specific electrode at one end of the
cell 24 without contacting the opposite polarity electrode. For example,
according to an exemplary embodiment, a negative current collector 40
(e.g., as shown in FIG. 4) may be connected to the exposed negative
electrode 38 at one end of the cell element 30 and a positive current
collector (not shown) may be connected to the exposed positive electrode
36 at the opposite end of the cell element 30.

[0064] According to an exemplary embodiment, the negative current
collector 40 electrically connects the negative electrode 38 to the
negative terminal 28 of the cell 24. The negative terminal 28 is
insulated from the cover 42 of the housing 25 by an insulator 45, as
shown in FIG. 4. According to an exemplary embodiment, the positive
current collector (not shown) electrically connects the positive
electrode 36 to a bottom of the housing 25. The housing 25 is
electrically connected to the cover 42 (e.g., as shown in FIG. 4), which
in turn is electrically connected to the positive terminal 26.

[0065] FIGS. 6-7 illustrate an exemplary embodiment of a wound cell
element 30 (e.g., a jelly roll) in which electrodes 36, 38 and separators
32, 34 (not shown) are wound around a member or element provided in the
form of a mandrel 50 (e.g., a body, center member, shaft, rod, tube
etc.). According to an exemplary embodiment, an adhesive or tape 48
(e.g., as shown in FIG. 6) may be used to position an
electrically-insulating wrap or film 46 (e.g., as shown in FIGS. 4 and 6)
around the cell element 30 in order to at least partially electrically
insulate the cell element 30 from the housing 25. According to an
exemplary embodiment, the film 46 is a polymide material such as is
commercially available under the trade name Kapton® from E. I. du
Pont de Nemours and Company.

[0066] According to an exemplary embodiment, the mandrel 50 is provided in
the form of an elongated hollow tube 52 and is configured to allow gases
from inside the electrochemical cell to flow from one end of the
electrochemical cell (e.g., the top) to the other end of the
electrochemical cell (e.g., the bottom). According to another exemplary
embodiment, the mandrel 50 may be provided as a solid tube.

[0067] The mandrel 50 is illustrated, for example, in FIG. 7 as being
provided within the center of the cell element 30. According to an
exemplary embodiment, the mandrel 50 does not extend all the way to the
very top and bottom of the cell element 30. According to other exemplary
embodiments, the mandrel 50 may extend all the way to the top and/or
bottom of the cell element 30.

[0068] Still referring to FIGS. 6-7, according to an exemplary embodiment,
the mandrel 50 includes at least one (i.e., one or more) element or drive
member 60 joined to an end of the hollow tube 52. According to an
exemplary embodiment, the drive members 60 are configured to electrically
insulate the hollow tube 52 from the electrodes 36, 38. According to
another exemplary embodiment, the hollow tube 52 may be provided in
electrical contact with one of the electrodes while being electrically
insulated from the other electrode. For example, according to an
exemplary embodiment, the hollow tube 52 may be electrically coupled to
the positive electrode 36 (or negative electrode 38), while the hollow
tube 52 is electrically isolated from the negative electrode 38 (or
positive electrode 36) by the drive member 60.

[0069] According to an exemplary embodiment, the drive members 60 are
formed from an electrically-insulating material such as a polymeric
material or other suitable material (e.g., a plastic resin) and the
hollow tube 52 is formed from an electrically (and thermally) conductive
material such as a metallic material or other suitable material (e.g.,
aluminum or aluminum alloy). According to another exemplary embodiment,
the drive members 60 are formed from an electrically (and thermally)
conductive material such as a metallic material or other suitable
material (e.g., aluminum or aluminum alloy) and the hollow tube 52 is
formed from an electrically-insulating material such as a polymeric
material or other suitable material (e.g., a plastic resin). According to
another exemplary embodiment, both the drive members 60 and the hollow
tube 52 are formed from an electrically-insulating material such as a
polymeric material or other suitable material (e.g., a plastic resin).

[0070] One advantageous feature of the mandrels 50 as described above is
that the drive members 60 coupled to the hollow tube 52 keep the positive
and negative electrodes 36, 38 electrically separated from each other.
Additionally, when the hollow tube 52 of the mandrel 50 is formed from a
relatively low cost material (e.g., a drawn aluminum tube or extruded
aluminum tube), the mandrel 50 may have a lower cost as compared to other
mandrels in which the entire assembly is made of a polymeric material.

[0071] According to other exemplary embodiments, other configurations of
the cell element 30 may be used that do not include the mandrel 50 or the
drive members 60 (e.g., a prismatic cell element). Additionally, while
the cell 24 in FIGS. 4 and 6 is shown according to an exemplary
embodiment as having the exposed negative electrode 38 proximate to the
top of the cell 24 and the exposed positive electrode 36 proximate to the
bottom of the cell 24, according to other exemplary embodiments, the
orientation of the cell element 30 (and thus the positions of the current
collectors) may be reversed. Additionally, according to other exemplary
embodiments, the terminals 26, 28 of the cell 24 may be provided on
opposite ends of the cell 24 (e.g., a negative terminal 28 may be
provided on the top of the cell 24 and a positive terminal 26 may be
provided on the bottom of the cell 24).

[0072] Referring now to FIGS. 8-9A, a member or element provided in the
form of a current collector or collector plate 140 is shown according to
an exemplary embodiment. According to an exemplary embodiment, the
current collector 140 is provided in the form of a generally flat member
with a plurality of legs or extensions 142 and an extension or tab 144
(formed, e.g., by a stamping operation, a laser cutting operation, etc.).
According to an exemplary embodiment, the current collector 140 may be
formed from a material having a thickness of between approximately 1 and
2 millimeters, but may have a greater or lesser thickness according other
exemplary embodiments. According to various exemplary embodiments, the
current collector 140 may be formed from any of a wide variety of
conductive materials such as aluminum or an aluminum alloy (e.g., for a
positive current collector), copper or a copper alloy (e.g., for a
negative current collector), nickel-plated copper or an alloy thereof,
etc.

[0073] As shown, the legs 142 are configured to extend across one end of
the cell element 30 to contact the edge of the exposed electrode (e.g.,
the negative electrode 38). According to another exemplary embodiment,
the legs 142 may extend only partially across the end of the cell element
30. While three legs 142 are shown in the exemplary embodiment of FIGS.
8-9A, according to other exemplary embodiments, the current collector 140
may have a greater or lesser number of legs 142.

[0074] As shown in FIG. 9A, according to an exemplary embodiment, the
extension or tab 144 is configured to be folded away from the cell
element 30 and at least partially back over the main body 141 of the
current collector 140. The tab 144 is configured to be coupled to the
housing of the cell or to a terminal of the cell to create a conductive
path between the electrode and the housing or terminal (e.g., similar to
that shown in FIG. 4). According to another exemplary embodiment, the tab
144 may be folded or bent at least partially over itself multiple times
(e.g., similar to that shown in FIG. 4). The tab 144 provides a
substantially flexible connection between the electrode of the cell
element 30 and the terminal or housing and allows the cell element 30 to
move relative to the terminal or housing if required.

[0075] As best seen in FIG. 8, the ends of the legs 142 may include a
rounded or curved shape to complement the perimeter of the cell element
30. According to other exemplary embodiments, the legs 142 (including the
ends of the legs) may have other shapes and/or sizes. According to an
exemplary embodiment, the legs 142 of the current collector are separated
from one another by an Angle A of approximately 120 degrees. According to
other exemplary embodiments, the legs 142 may be separated from one
another by a greater or smaller angle.

[0076] According to an exemplary embodiment, the current collector 140 may
be coupled to the electrode with a welding operation (e.g., a laser
welding operation) along the legs 142 of the current collector 140 (e.g.,
such as along weld lines 146 as shown in FIG. 8). As such, the welding
occurs radially with respect to the end of the cell element 30. This
allows for more efficient current flow from the electrode of the cell
element 30 to the current collector 140, because the edge of the wound
electrode is coupled (e.g., welded) to the current collector 140 (via the
legs 142) multiple times. Additionally, radial welds on a wound cell
element (such as shown in FIG. 9) allow the weld to occur substantially
perpendicular to the edge of the electrode, providing for better weld
control and repeatability of the weld from one cell to the next.
According to an exemplary embodiment, the welding of the current
collector 140 to the electrode is done prior to the folding of the tab
144, but may occur at a different time according to other exemplary
embodiments.

[0077] Referring now to FIGS. 10-12B, a current collector 240 is shown
according to another exemplary embodiment. The current collector 240 is
similar to the current collector 140 of FIGS. 8-9, except the current
collector 240 of FIGS. 10-12B is formed as a relatively narrow elongated
strip of material (to allow for the efficient use of material). According
to an exemplary embodiment, the current collector 240 may be formed from
a material having a thickness of between approximately 1 and 2
millimeters, but may have a greater or lesser thickness according other
exemplary embodiments. According to various exemplary embodiments, the
current collector 240 may be formed from any of a wide variety of
conductive materials such as aluminum or an aluminum alloy (e.g., for a
positive current collector), copper or a copper alloy (e.g., for a
negative current collector), nickel-plated copper or an alloy thereof,
etc.

[0078] The legs 242 are formed (e.g., by a stamping operation, a laser
cutting operation, etc.) by a series of generally parallel cuts at one
end of the strip of material in a longitudinal direction. To form the
current collector 240, according to an exemplary embodiment, the outer
legs 242 are folded or otherwise manipulated outward at an angle (see
FIG. 12) of approximately 120 degrees from one another. According to
other exemplary embodiments, the outer legs may be folded at an angle
that is greater or smaller than 120 degrees.

[0079] According to an exemplary embodiment, the legs 242 of the current
collector 240 are configured to extend across the end of the electrode of
the cell element 30 to contact the edge of the exposed electrode (e.g.,
the negative electrode or the positive electrode). According to another
exemplary embodiment, the legs 242 may extend only partially across the
end of the wound electrode. While three legs 242 are shown in the
exemplary embodiment of FIGS. 10-12, according to other exemplary
embodiments, the current collector 240 may have a greater or lesser
number of legs.

[0080] As shown in FIG. 12A, according to one exemplary embodiment, the
outer legs 242 may be bent or folded under the main body 241 of the
current collector 240 such that the outer legs 242 are substantially
parallel to the inner leg 242. As shown in FIG. 12B, according to another
exemplary embodiment, the outer legs 242 may be bent or folded under the
main body 241 of the current collector 240 such that the outer legs 242
are at an angle with respect to the plane of the main body 241 (e.g.,
such as Angle B as shown in FIG. 13A). Additionally, as shown in FIG.
12B, the inner leg 242 may be bent or folded towards the cell element 30
such that the inner leg 242 is at an angle with respect to the plane of
the main body 241 (e.g., such as Angle B as shown in FIG. 13A). According
to an exemplary embodiment, the inner leg 242 may be bent or folded
before, after, or consecutively with the bending or folding of the outer
legs 242.

[0081] The current collector 240 may be coupled to the electrode with a
welding operation (e.g., a laser welding operation) along the legs 242 of
the current collector 240 (e.g., such as along weld lines 246 as shown in
FIG. 12). As such, the welding occurs radially with respect to the edge
of the electrode of the cell element 30. Similarly to as stated above,
radial welding allows for more efficient current flow from the electrode
of the cell element 30 to the current collector 240, and for better weld
control and repeatability of the weld from one cell to the next.
According to an exemplary embodiment, the welding of the current
collector 240 to the electrode is done prior to the folding of the tab
244, but may occur at a different time according to other exemplary
embodiments.

[0082] The current collector 240 also includes an extension or tab 244
that is configured to be folded away from the cell element 30 and/or at
least partially back over the main body 241 of the current collector 240
(e.g., such as shown in FIGS. 13A and 13B). The tab 244 is configured to
be coupled to the housing of the cell or to a terminal of the cell to
create a conductive path between the electrode and the housing or
terminal (e.g., similar to that as shown in FIG. 4). According to another
exemplary embodiment, the tab 244 may be folded or bent at least
partially over itself multiple times (e.g., similar to that as shown in
FIG. 4). The tab 244 provides a substantially flexible connection between
the electrode and the terminal or housing and allows the cell element 30
to move relative to the terminal or housing.

[0083] Referring to FIGS. 13A and 13B, the inner leg 242 of the current
collector 240 may be at an angle with respect to the plane of the tab
244, shown as Angle B (for clarity, the outer legs 242 are not shown). It
is noted that the legs 142 of the current collector 140 (e.g., as shown
in FIGS. 8-9A) may also be at an angle with respect to the plane of the
tab (e.g., such as shown in FIGS. 13A and 13B). For clarity, only the
current collector 240 is discussed below, although one of ordinary skill
in the art would know that the embodiment discussed below may also apply
to the embodiment shown in FIGS. 8-9A or other embodiments not discussed.

[0084] Referring to FIGS. 13A and 13B, Angle B is chosen so that the legs
242 of the current collector 240 bend or crush the edge or side of the
electrode (e.g., the negative electrode 38) as the legs 242 make contact
with the edge of the electrode as the legs 242 are brought down to
contact the edge of the electrode (see, e.g., FIG. 13B). Because the
electrodes of the cell element 30 are wound, each of the electrodes will
have multiple portions extending from the edge of each electrode. The
legs 242 of the current collector 240 may then be coupled to the multiple
portions of the edge of the electrode by a welding operation (e.g., a
laser welding operation).

[0085] The multiple portions of the edge of the electrode are bent or
crushed so that they contact one another to create a substantially
continuous surface. The substantially continuous surface allows for
better control of the penetration of the weld. By controlling the
penetration of the weld, a stronger, higher quality, and more repeatable
weld may be formed than is possible with an electrode that hasn't been
deformed (e.g., an electrode that hasn't had the multiple portions of the
edge of the electrode bent to touch one another). The tab 244 of the
current collector 240 is then coupled to the housing of the cell or to
the terminal of the cell to create a conductive path between the
electrode and the housing or terminal.

[0086] To create a high quality and repeatable weld between the current
collector 240 and the electrode, it is desirable for the legs 242 of the
current collector 240 to contact as many of the multiple portions of the
edge of the electrode as possible. According to an exemplary embodiment,
Angle B is between approximately 0 degrees and 30 degrees, but may have
an angle that is greater or smaller according to other exemplary
embodiments. According to a particular exemplary embodiment, Angle B is
between approximately 15 and 25 degrees. According to another particular
exemplary embodiment, Angle B is approximately 20 degrees.

[0087] Referring now to FIGS. 14-17, a member or element provided in the
form of a current collector or collector plate 340 is shown according to
another exemplary embodiment. According to one exemplary embodiment, the
current collector 340 is provided as a disc-like member that includes one
or more projections, ridges, or protrusions 342 that extend along one
side of the current collector 340. The protrusions 342 of the current
collector 340 have corresponding grooves, valleys, troughs, depressions,
etc. on the opposite side of the current collector 340. According to
other exemplary embodiments, the protrusions 342 may not have
corresponding grooves, valleys, troughs, depressions, etc. on the
opposite side of the current collector 340. According to one exemplary
embodiment, the protrusions 342 are configured to crush or compress the
multiple portions of the edge of the exposed electrode (e.g., the
positive electrode 36) at an end of the cell element 30 so that the
multiple portions contact one another (e.g., as shown in FIG. 18B).

[0088] The current collector 340 may be formed (e.g., extruded, stamped,
etc.) such that one or more protrusions 342, shown as generally V-shaped
ridges, extend from a surface of the current collector 340. According to
an exemplary embodiment, a tip or edge of the protrusions 342 may have a
pointed profile. According to another exemplary embodiment, the tip or
edge of the protrusions 342 may have a rounded profile. According to
other exemplary embodiments, the protrusions 342 may extend all the way
across the current collector 340 (e.g., as shown in FIG. 14) or may
extend only partially across the current collector 340.

[0089] According to another exemplary embodiment, the current collector
340 may substantially match the size and shape of the end of the cell
element 30. According to other exemplary embodiments, the current
collector 340 may be provided in other shapes and/or sizes (e.g., the
current collector 340 may cover only a portion of the end of the cell
element 30). According to an exemplary embodiment, the current collector
340 may be formed from a material having a thickness of between
approximately 1 and 2 millimeters, but may have a greater or lesser
thickness according other exemplary embodiments. According to various
exemplary embodiments, the current collector 340 may be formed from any
of a wide variety of conductive materials such as aluminum or an aluminum
alloy (e.g., for a positive current collector), copper or a copper alloy
(e.g., for a negative current collector), nickel-plated copper or an
alloy thereof, etc.

[0090] The current collector 340 is coupled to the exposed edge of an
electrode (e.g., the positive electrode 36) of the cell element 30 with a
welding operation (e.g., a laser welding operation). According to an
exemplary embodiment, the current collector 340 is welded to the
electrode along the protrusions 342 of the current collector 340 (e.g.,
such as along weld lines 346 as shown in FIG. 14).

[0091] Referring to FIGS. 18A-18B, the protrusions 342 of the current
collector 340 are configured to crush, bend, or otherwise deform the
multiple portions of the exposed edge of the positive electrode 36 when
the current collector 340 is coupled to the cell element 30. The
protrusions 342 cause the multiple portions of the edge of the electrode
to contact each other to create a substantially continuous surface. The
substantially continuous surface allows for better control of the
penetration of the weld. By controlling the penetration of the weld, a
stronger, higher quality, and more repeatable weld may be formed than is
possible with an electrode that has not been deformed.

[0092] A surface 344 of the current collector 340 is then coupled to the
housing of the cell or to the terminal to create a conductive path
between the electrode and the housing or terminal According to an
exemplary embodiment, the surface 344 may include a hole or aperture 348
(e.g., as shown in FIG. 17) that is generally aligned with the center of
the cell element 30.

[0093] Referring now to FIGS. 19 and 19A, a member or element provided in
the form of a current collector or collector plate 440 is shown according
to another exemplary embodiment. The current collector 440 may be formed
by a stamping operation (e.g., from a sheet metal material). According to
an exemplary embodiment, the current collector 440 may be formed from a
material having a thickness of between approximately 1 and 2 millimeters,
but may have a greater or lesser thickness according other exemplary
embodiments. According to various exemplary embodiments, the current
collector 440 may be formed from any of a wide variety of conductive
materials such as aluminum or an aluminum alloy (e.g., for a positive
current collector), copper or a copper alloy (e.g., for a negative
current collector), nickel-plated copper or an alloy thereof, etc.

[0094] According to an exemplary embodiment, the current collector 440
includes one or more lower portions 442 that are configured to be coupled
to an electrode (e.g., the positive electrode 36). The current collector
440 also includes one or more upper portions 444 that are configured to
be coupled to the housing of the cell or to the terminal of the cell to
create a conductive path between the electrode and the housing or
terminal According to the exemplary embodiment shown in FIG. 19, the
current collector 440 includes four lower portions 442 and four upper
portions 444. According to other exemplary embodiments, the current
collector 440 may have greater or fewer upper and/or lower portions.

[0095] According to an exemplary embodiment, each of the lower portions
442 are connected to the upper portion by a member shown as a sidewall or
shoulder 450. As shown in FIG. 19, the shoulders 450 may have a generally
rounded profile and may smoothly transition from the lower portion 442 to
the upper portion 444. According to another exemplary embodiment, each of
the lower portions 442 includes at least one projection or protrusion
452.

[0096] According to an exemplary embodiment, the current collector 440 is
coupled to exposed portions of the edge of the positive electrode 36 by a
welding operation (e.g., a laser welding operation) along the lower
portions 442 of the current collector 440 (e.g., such as along weld lines
446 as shown in FIG. 19A). According to one exemplary embodiment, the
lower portions 442 may contact, bend, or deform the exposed portions of
the edge of the electrode 36 prior to welding (e.g., similar to that as
shown in FIG. 18B). According to another exemplary embodiment, the
exposed portions of the edge of the electrode 36 may be deformed prior to
coupling the current collector 440 to the electrode 36. The current
collector 440 may then be coupled to the cell housing or a terminal with
another welding operation along the upper portions 444 of the current
collector 440.

[0097] Referring now to FIGS. 20 and 20A, a member or element provided in
the form of a current collector or collector plate 540 is shown according
to another exemplary embodiment. The current collector 540 may be formed
by a stamping operation (e.g., from a sheet metal material). According to
an exemplary embodiment, the current collector 540 may be formed from a
material having a thickness of between approximately 1 and 2 millimeters,
but may have a greater or lesser thickness according other exemplary
embodiments. According to various exemplary embodiments, the current
collector 540 may be formed from any of a wide variety of conductive
materials such as aluminum or an aluminum alloy (e.g., for a positive
current collector), copper or a copper alloy (e.g., for a negative
current collector), nickel-plated copper or an alloy thereof, etc.

[0098] According to an exemplary embodiment, the current collector 540
includes one or more lower portions 542 that are configured to be coupled
to an electrode (e.g., the positive electrode 36). The current collector
540 also includes one or more upper portions 544 that are configured to
be coupled to the housing of the cell or to the terminal of the cell to
create a conductive path between the electrode and the housing or
terminal According to the exemplary embodiment shown in FIG. 20, the
current collector 540 includes four lower portions 542 and four upper
portions 544. According to other exemplary embodiments, the current
collector 540 may have greater or fewer upper and/or lower portions.
According to an exemplary embodiment, an opening or aperture 548 is
included in the current collector 540. The aperture 548 has a central
axis that is generally aligned with the central axis of the cell element
30.

[0099] According to an exemplary embodiment, each of the lower portions
542 are connected to the upper portion by a member shown as a sidewall or
shoulder 550. As shown in FIG. 20, the shoulders 550 may have a generally
rounded profile and may smoothly transition from the lower portion 542 to
the upper portion 544. According to another exemplary embodiment, each of
the lower portions 542 extends to the perimeter of the cell element 30,
while the upper portions 544 extend only partially across the cell
element 30. According to various exemplary embodiments, the lower
portions 542 and/or upper portions 544 may have other configurations
(e.g., the lower portions 542 may extend only partially across the end of
the cell element, the upper portions 544 may extend all the way across
the end of the cell element, etc.)

[0100] According to an exemplary embodiment, the current collector 540 is
coupled to exposed portions of the edge of the positive electrode 36 by a
welding operation (e.g., a laser welding operation) along the lower
portions 542 of the current collector 540 (e.g., such as along weld lines
546 as shown in FIG. 20A). According to one exemplary embodiment, the
lower portions 542 may contact, bend, or deform the exposed portions of
the edge of the electrode 36 prior to welding (e.g., similar to that as
shown in FIG. 18B). According to another exemplary embodiment, the
exposed portions of the edge of the electrode 36 may be deformed prior to
coupling the current collector 540 to the electrode 36. The current
collector 540 may then be coupled to the cell housing or a terminal with
another welding operation along the upper portions 544 of the current
collector 540.

[0101] Referring now to FIG. 21, a member or element provided in the form
of a current collector or collector plate 640 is shown according to an
exemplary embodiment. The current collector 640 may be formed from a
stamping process, a laser cutting process, or other suitable process.
According to an exemplary embodiment, the current collector 640 may be
formed from a material having a thickness of between approximately 1 and
2 millimeters, but may have a greater or lesser thickness according other
exemplary embodiments. According to various exemplary embodiments, the
current collector 640 may be formed from any of a wide variety of
conductive materials such as aluminum or an aluminum alloy (e.g., for a
positive current collector), copper or a copper alloy (e.g., for a
negative current collector), nickel-plated copper or an alloy thereof,
etc.

[0102] As shown in FIG. 21, the current collector 640 includes a first or
outer member 648 that is connected to a second or inner member 644 by a
plurality of members or arms 642. As shown in FIG. 21, the outer member
648 is connected to the inner member 644 by four arms 642. According to
other exemplary embodiments, the outer member 648 may be connected to the
inner member 644 by a greater or lesser number of arms having the same or
different configuration as shown in FIG. 21.

[0103] According to the exemplary embodiment shown in FIG. 21, the outer
member 648 is provided in the form of a ring or ring-like structure. In
the embodiment shown, a perimeter of the outer member 648 substantially
matches/aligns with the perimeter of the cell element 30. Also according
to the exemplary embodiment shown in FIG. 21, the inner member 644 has a
generally circular shape.

[0104] According to the exemplary embodiment shown in FIG. 21, each of the
plurality of arms 642 includes a first portion connected to the outer
member 648 and a second portion connected to a member or extension 650.
The extension 650 connects the arm 642 to the inner member 644. As shown
in FIG. 21, the first portion of each of the arms 642 extends out from
the outer member 648 in a generally perpendicular direction (i.e., the
first portion extends generally perpendicular out from the outer member
648). According to an exemplary embodiment, the extension 650 extends out
from each of the arms 642 at a point between first and second ends of the
arms 642 (e.g., at an approximate midpoint between the first and second
ends of the arms 642). According to an exemplary embodiment, the inner
member 644 can move relative to the outer member 648 because of the
flexibility of the arms 642 and/or the extensions 650.

[0105] According to an exemplary embodiment, the arms 642 and/or the outer
member 648 are coupled (e.g., by laser welding) to and edge of an
electrode of the cell element 30 (e.g., such as along weld lines 646 as
shown in FIGS. 21 and 24C) and the inner member 644 is coupled (e.g., by
laser welding) to a portion of the housing of the cell or a terminal of
the cell (e.g., such as along weld lines 658 as shown in FIG. 24C). As
shown in FIG. 24C, the weld lines 646 of the arms 642 and the weld lines
658 of the inner member 644 do not align when the vent 70 is deployed. In
particular, the lines 642 and 658 are non-parallel (e.g., skewed) as a
result of circumferential movement (e.g., twisting) of the arms 642 about
an axis 638 of the current collector 640. In other words, when the vent
70 deploys, the arms 642 move in an axial direction along the axis 638 as
well as in a circumferential direction about the axis 638. According to
an exemplary embodiment, the welding of the arms 642 is performed
radially across the edge of the electrode of the cell element 30 (e.g.,
as shown in FIG. 21). According to another exemplary embodiment, the
inner member 644 is coupled to the edge of the electrode of the cell
element 30 and the arms 642 and/or the outer member 648 are coupled to
the housing or the terminal.

[0106] According to an exemplary embodiment, the geometry of the outer
member 648, arms 642, extensions 650, and inner member 644 define a
plurality of apertures or slots. These apertures or slots allow the
current collector 640 to substantially flex (e.g., move, bend, deflect,
etc.) if required (e.g., when a vent deploys from the bottom of the
housing). For example, as shown in FIG. 24B, the inner member 644 is
configured to flex with respect to the outer member 648 when the vent 70
deploys from the end of the cell 24.

[0107] Having a flexible current collector allows for increased length of
the cell element inside the housing (e.g., to maximize the power capacity
of the cell). The flexible current collector also allows the cell element
to remain substantially fixed during deployment of a vent. The flexible
current collector also helps to isolate the vent from shock and vibration
during handling and assembly and during use of the cell.

[0108] Referring now to FIG. 22, a current collector 740 is shown
according to another exemplary embodiment. The current collector 740 is
provided with similar but slightly different geometry than that of the
current collector 640 shown in FIG. 21. The current collector 740 may be
formed from a stamping process, a laser cutting process, or other
suitable process. According to an exemplary embodiment, the current
collector 740 may be formed from a material having a thickness of between
approximately 1 and 2 millimeters, but may have a greater or lesser
thickness according other exemplary embodiments. According to various
exemplary embodiments, the current collector 740 may be formed from any
of a wide variety of conductive materials such as aluminum or an aluminum
alloy (e.g., for a positive current collector), copper or a copper alloy
(e.g., for a negative current collector), nickel-plated copper or an
alloy thereof, etc.

[0109] As shown in FIG. 22, the current collector 740 includes a first or
outer member 748 that is connected to a second or inner member 744 by a
plurality of members or arms 742. As shown in FIG. 22, the outer member
748 is connected to the inner member 744 by four arms 742. According to
other exemplary embodiments, the outer member 748 may be connected to the
inner member 744 by a greater or lesser number of arms.

[0110] According to the exemplary embodiment shown in FIG. 22, the outer
member 748 is provided in the form of a ring or ring-like structure.
According to an exemplary embodiment, a perimeter of the outer member 748
substantially matches/aligns with a perimeter of the cell element.
According to the exemplary embodiment shown in FIG. 22, the inner member
744 has a generally circular shape.

[0111] According to the exemplary embodiment shown in FIG. 22, each of the
plurality of arms 742 includes a first portion connected to the outer
member 748 and a second portion connected to a member or extension 750.
The extension 750 connects the arm 742 to the inner member 744. As shown
in FIG. 22, the first portion of each of the arms 742 extends out from
the outer member 748 in a generally perpendicular direction (i.e., the
first portion extends generally perpendicular out from the outer member
748). According to an exemplary embodiment, the extension 750 extends out
from each of the arms 742 at a point between first and second ends of the
arms 742 (e.g., at a point near the first end of the arms 742). According
to an exemplary embodiment, the inner member 744 can move relative to the
outer member 748 because of the flexibility of the arms 742 and/or the
extensions 750.

[0112] According to an exemplary embodiment, the arms 742 and/or the outer
member 748 are coupled (e.g., by laser welding) to an edge of an
electrode of the cell element and the inner member 744 is coupled (e.g.,
by laser welding) to a portion of the housing of the cell or a terminal
of the cell. According to an exemplary embodiment, the welding of the
arms 742 is performed radially across the end of the cell element.
According to another exemplary embodiment, the inner member 744 is
coupled to the edge of the electrode of the cell element and the arms 742
and/or the outer member 748 are coupled to the housing or the terminal.

[0113] According to an exemplary embodiment, the geometry of the outer
member 748, arms 742, extensions 750, and inner member 744 define a
plurality of apertures or slots. These apertures or slots allow the
current collector 740 to substantially flex (e.g., move, bend, deflect,
etc.) if required (e.g., when a vent deploys from the bottom of the
housing). For example, the inner member 744 is configured to flex with
respect to the outer member 748 (or vice-versa). It should be noted that
the arms 742 are rotationally symmetric. For example, rotation of the
current collector 742 approximately 90 degrees about the axis 638 results
in a substantially identical orientation.

[0114] Referring now to FIG. 23, a current collector 840 is shown
according to another exemplary embodiment. The current collector 840 may
be formed from a stamping process, a laser cutting process, or other
suitable process. According to an exemplary embodiment, the current
collector 840 may be formed from a material having a thickness of between
approximately 1 and 2 millimeters, but may have a greater or lesser
thickness according other exemplary embodiments. According to various
exemplary embodiments, the current collector 840 may be formed from any
of a wide variety of conductive materials such as aluminum or an aluminum
alloy (e.g., for a positive current collector), copper or a copper alloy
(e.g., for a negative current collector), nickel-plated copper or an
alloy thereof, etc.

[0115] As shown in FIG. 23, the current collector 840 includes a first or
outer member 848 that is connected to a second or inner member 844. As
shown in FIG. 23, there are two outer members 848 that are connected to
the inner member 844. According to other exemplary embodiments, there may
be a greater or lesser number of outer members 848. According to an
exemplary embodiment, each of the outer members 848 are connected to a
member or element shown as an arm 842 that in turn is connected to the
inner member 844. According to the exemplary embodiment shown in FIG. 23,
the outer member 848 is provided in the form of an enlarged portion of
outer arm 842. The arm 842 has a spiral shape about the inner member 844.
That is, the arm 842 emanates from the inner member 844 and has an
arcuate shape from the inner member 844 to the outer member 848. As
shown, the arm 842 increases in width from the inner member to the outer
member 848.

[0116] As shown in FIG. 23, each of the arms 842 includes an outer portion
850 and an inner portion 852. According to an exemplary embodiment, an
outer portion 850 of the arm 842 substantially matches/aligns with a
perimeter of the cell element. As shown in FIG. 23, each of the inner
portions 852 of the arms 842 double back along at least a portion of the
outer portion 850 of the arms 842 before connecting to the inner member
844.

[0117] According to an exemplary embodiment, the outer portion 850 of the
arms 842 and/or the outer members 848 are coupled (e.g., by laser
welding) to an edge of an electrode of the cell element and the inner
member 844 is coupled (e.g., by laser welding) to a portion of the
housing of the cell or to a terminal of the cell. According to another
exemplary embodiment, the inner member 844 is coupled to the edge of an
electrode of the cell element and the outer portion 850 of the arms 842
and/or the outer member 848 are coupled to the housing or the terminal.

[0118] According to an exemplary embodiment, the geometry of the outer
members 848, arms 842, and inner member 844 define a plurality of
apertures or slots. These apertures or slots allow the current collector
840 to substantially flex (e.g., move, bend, deflect, etc.) if required
(e.g., when a vent deploys from the bottom of the housing). For example,
the inner member 844 is configured to flex with respect to the outer
member 848 (or vice-versa). It should be noted that the arms 842 are
rotationally symmetric. For example, rotation of the current collector
742 approximately 180 degrees about the axis 638 results in a
substantially identical orientation.

[0119] Referring now to FIGS. 24A-24D, according to an exemplary
embodiment, the cell 24 includes a vent 70. The vent 70 is configured to
allow gases and/or effluent to exit the cell 24 once the pressure inside
the cell 24 reaches a predetermined amount (e.g., during a rise in cell
temperature). When the vent 70 deploys (e.g., activates, opens,
separates, etc.), the gases and/or effluent inside the cell 24 exit the
cell 24 in order to lower the pressure inside the cell 24 (e.g., as
represented by arrows 76 shown in FIG. 24B). According to an exemplary
embodiment, the vent 70 acts as a safety device for the cell 24 during a
high pressure occurrence.

[0120] According to an exemplary embodiment, the vent 70 is located in the
bottom or bottom portion of the housing 25. According to other exemplary
embodiments, the vent 70 may be located elsewhere (e.g., such as in the
lid or cover of the cell). According to another exemplary embodiment, the
vent 70 may be located in a cover or bottom that is a separate component
from the housing 25 that in turn is coupled to the housing 25 (e.g., by a
welding operation).

[0121] According to an exemplary embodiment, the bottom of the housing 25
may include a ridge, projection, or ring of material 74 (e.g., as shown
in FIGS. 24A and 24B) to prevent fracture of the vent 70 during handling
and/or assembly of the cell 24. The ring of material 74 provides for a
clearance space between the vent 70 and a surface that the cell 24 is set
upon. According to an exemplary embodiment, the clearance space is
configured to prevent the vent 70 from being accidentally bumped (and
deployed) during handling and/or assembly of the cell 24.

[0122] As shown in FIG. 24A, the vent 70 includes at least one annular
fracture groove 72 (e.g., ring, trough, pressure point, fracture point,
fracture ring, etc.). According to an exemplary embodiment, the annular
fracture groove 72 has a V-shaped bottom and is configured to break away
(i.e., separate) from the bottom of the housing 25 when the vent 70
deploys. According to other exemplary embodiments, the bottom of the
annular fracture groove 72 may have another shape (e.g., rounded shape,
curved shape, U-shape, etc.).

[0123] As stated earlier, the vent 70 is configured to deploy in the
direction along or parallel to the axis 638 once the pressure inside the
cell 24 reaches a predetermined amount. When the vent 70 deploys, the
annular fracture groove 72 fractures and separates the vent 70 from the
rest of the bottom of the housing 25, allowing the internal gases and/or
effluent to escape the cell (e.g., as shown in FIG. 24B). By having the
vent 70 separate from the bottom of the housing 25, the vent 70 acts as a
current interrupt or current disconnect device. This is because the
separation of the vent 70 from the bottom of the housing 25 along the
axis 638 disrupts the flow of current from the cell element 30 (through
the positive current collector 640) to the housing 25. In this way, the
vent 70 acts not only as an over-pressure safety device, but also as a
current disconnect device. In order to help insulate the cell element 30
and the current collector 640 from the housing 25, the insulative wrap 46
may include an extension 47 provided between the current collector 640
and the bottom of the housing 25.

[0124] According to an exemplary embodiment, the vent 70 (e.g., the
annular fracture groove 72) is formed by tooling located external the
housing 25. The tooling tolerance is only affected by one side of the
tool, allowing for a more consistent annular fracture groove 72,
resulting in a more consistent and repeatable opening of the vent 70. The
depth, shape, and size of the fracture groove 72 may be easily modified
simply by changing the tooling. Additionally, the vent 70 is easy to
clean and inspect since the vent 70 (and annular fracture groove 72) is
located on an external side of the housing 25.

[0125] According to one exemplary embodiment, the cell element 30 does not
move during deployment of the vent 70 (i.e., the cell element remains
stationary). According to such exemplary embodiments, flexible current
collectors may be utilized (e.g., such as the current collector 640 shown
in FIGS. 21 and 24A-C, the current collector 740 shown in FIG. 22, or the
current collector 840 shown in FIG. 23). According to other exemplary
embodiments, the cell element 30 may move in order to help deploy the
vent 70 (e.g., by "pushing" or "punching" the current collector through
the vent). According to such exemplary embodiments, non-flexible current
collectors may be utilized (e.g., such as the current collector 340 shown
in FIGS. 14-17, the current collector 440 shown in FIG. 19, or the
current collector 540 shown in FIG. 20.).

[0126] Referring now to FIG. 24D, a housing 125 for an electrochemical
cell is shown according to another exemplary embodiment. The housing 125
includes a vent 170 provided in a bottom portion of the housing 125.
According to other exemplary embodiments, the vent 170 may be provided
elsewhere (e.g., such as in the lid or cover of the cell). According to
another exemplary embodiment, the vent 170 may be located in a cover or
bottom that is a separate component from the housing 125 that in turn is
coupled to the housing 125 (e.g., by a welding operation).

[0127] According to an exemplary embodiment, the bottom of the housing 125
may include a ridge, projection, or ring of material 174 to prevent
fracture of the vent 170 during handling and/or assembly of the cell. The
ring of material 174 provides for a clearance space between the vent 170
and a surface that the cell is set upon. According to an exemplary
embodiment, the clearance space is configured to prevent the vent 170
from being accidentally bumped (and deployed) during handling and/or
assembly of the cell.

[0128] As shown in FIG. 24D, the vent 170 includes at least one annular
fracture groove 172 (e.g., ring, trough, pressure point, fracture point,
fracture ring, etc.). According to an exemplary embodiment, the annular
fracture groove 172 has a V-shaped bottom and is configured to break away
(i.e., separate) from the bottom of the housing 125 when the vent 170
deploys. According to other exemplary embodiments, the bottom of the
annular fracture groove 172 may have another shape (e.g., rounded shape,
curved shape, U-shape, etc.).

[0129] Referring now to FIGS. 25-29, a member or element provided in the
form of a current collector or collector plate 940 is shown according to
an exemplary embodiment. As shown best in FIG. 29, the current collector
940 is used to conductively couple an end of the electrode (e.g., the
negative electrode 38) of the cell element 30 to a terminal (e.g., the
negative terminal 28).

[0130] The current collector 940 may be formed from a stamping process, a
laser cutting process, or other suitable process. According to an
exemplary embodiment, the current collector 940 may be formed from a
material having a thickness of between approximately 1 and 2 millimeters,
but may have a greater or lesser thickness according other exemplary
embodiments. According to various exemplary embodiments, the current
collector 940 may be formed from any of a wide variety of conductive
materials such as aluminum or an aluminum alloy (e.g., for a positive
current collector), copper or a copper alloy (e.g., for a negative
current collector), nickel-plated copper or an alloy thereof, etc.

[0131] Referring to FIGS. 26-27, the current collector 940 is provided in
the form of a generally flat member having a main body 942. Extending out
from one end of the main body 942 is at least one tab or extension 944
(shown in FIG. 27 as at least partially folded over the main body 942).
According to an exemplary embodiment, the tab 944 is at least partially
folded over the main body 942 multiple times (e.g., similar to the tab 44
shown in FIG. 4). According to an exemplary embodiment, the main body 942
includes a hole or aperture 950 (e.g., as shown in FIG. 26). The aperture
950 may be provided as generally aligned with the center of the cell
element 30.

[0132] According to an exemplary embodiment, the tab 944 is configured to
be coupled to a terminal (e.g., the negative terminal) of the cell (e.g.,
by laser welding). The tab 944 provides a substantially flexible
connection between the electrode of the cell element and the terminal and
allows the cell element to move relative to the terminal or housing if
required.

[0133] According to an exemplary embodiment, the current collector 940
also includes a plurality of members or extensions shown as arms 948 that
are configured to project or extend out from the main body 942 of the
current collector 940. The arms 948, along with the main body 942 of the
current collector 940, extend out across one end of the cell element 30
(e.g., to contact the edge of the negative electrode 38 such as shown in
FIG. 25). According to another exemplary embodiment, the arms 948 and
main body 942 of the current collector 940 may extend only partially
across the end of the cell element 30. While two arms 948 are shown in
the exemplary embodiment of FIGS. 25-29, according to other exemplary
embodiments, the current collector 940 may have a greater or lesser
number of arms 948.

[0134] As best seen in FIG. 25, the outer edge of the arms 948 may include
a rounded or curved shape to complement the perimeter of the cell element
30. According to other exemplary embodiments, the arms 948 (including the
ends of the arms) may have other shapes and/or sizes. The current
collector 940 may be coupled to the electrode 38 with a welding operation
(e.g., a laser welding operation) along the arms 948 and main body 942 of
the current collector 940.

[0135] According to an exemplary embodiment, radial welds are used (e.g.,
such as along weld lines 946 as shown in FIG. 25) to couple the current
collector 940 to the electrode 38. According to one exemplary embodiment,
the radial welds extend from the center of the main body 942 out to the
outer edges of the main body 942 and arms 948. According to other
exemplary embodiments, the welds (radial or otherwise) may be formed
differently. According to an exemplary embodiment, the welding of the
current collector 940 to the electrode is done prior to the folding of
the tab 944, but may occur at a different time according to other
exemplary embodiments.

[0136] The use of radial welds (i.e., welds that are radial with respect
to the edge of the electrode of the cell element 30) allows for more
efficient current flow from the electrode of the cell element 30 to the
current collector 940 in that all of the portions of the edge of the
wound electrode are coupled (e.g., welded) to the current collector 940
(via the arms 948 and the main body 942). Additionally, radial welds on a
wound cell element (such as shown in FIG. 25) allow the weld to occur
substantially perpendicular to the edge of the electrode, providing for
better weld control and repeatability of the weld from one cell to the
next.

[0137] While the current collectors of FIGS. 8-13B and 25-29 are generally
shown as being coupled to a negative electrode, according to other
exemplary embodiments they may be coupled to a positive electrode.
Likewise, while the current collectors of FIGS. 14-24C are generally
shown as coupled to a positive electrode, according to other exemplary
embodiments they may be coupled to a negative electrode. Furthermore,
while the current collectors shown in FIGS. 8-29 are configured for use
with wound cell elements, according to another exemplary embodiment, the
current collectors may also be used with a series of flat plates (e.g.,
prismatic cells) or other cell configurations.

[0138] According to various exemplary embodiments, the current collectors
shown in FIGS. 8-29 may be formed from a relatively thin sheet of
conductive material (e.g., by a stamping operation, a laser cutting
operation, etc.) or may be formed by an extrusion process. According to
various exemplary embodiments, the current collectors may be
substantially rigid or may include a flexible or pliable portion (such
as, e.g., the tabs shown in FIGS. 8-13 and 25-29 or the arms shown in
FIGS. 21-23).

[0139] Referring now to FIG. 30, an assembly process used to make a
battery or electrochemical cell is shown according to an exemplary
embodiment. In a first step 1010, the separators and electrodes are wound
around the mandrel to form the cell element in a jelly roll
configuration. In a second step 1020A/1020B, the positive and negative
current collectors are electrically or conductively coupled (e.g., by a
welding operation such as laser welding) to the positive and negative
electrode ends of the jelly roll, respectively. According to various
exemplary embodiments, the step 1020A may occur before, after, or
concurrent with the step 1020B.

[0140] In a third step 1030, the jelly roll is inserted into the cell
housing. In a fourth step 1040, the positive current collector is
electrically or conductively coupled (e.g., by a welding operation) to
the base of the cell housing. In a fifth step 1050, the negative current
collector is electrically or conductively coupled (e.g., by a welding
operation) to the insulated terminal of the cap of the cell. In a sixth
step 1060, the cap of the cell is coupled to the housing of the cell
(e.g., by a welding operation).

[0141] According to an exemplary embodiment, a current collector or plate
for an electrochemical cell includes a member having a first surface and
a second surface opposite the first surface. The second surface comprises
at least one projection. The member is configured to be coupled to an
electrode of the cell, the electrode having a wound configuration. The at
least one projection is configured to engage an offset edge of the
electrode so that the member can be welded to the cell.

[0142] Another embodiment of the invention relates to a current collector
or plate for an electrochemical cell including a member. The member
includes a main body and at least two legs extending out from a first end
of the body. The legs are configured to engage an offset edge of a wound
electrode of the cell so that the member can be welded to the cell.

[0143] One embodiment of the invention relates to a substantially flexible
current collector for an electrochemical cell. The current collector
includes a plurality of members coupled to a cell element and an inner
ring coupled to a bottom of a housing.

[0144] Another embodiment of the invention relates to a current collector
for an electrochemical cell. The current collector includes a main body
and at least one arm extending out from a first end of the main body. The
main body and the at least one arm are configured to be conductively
coupled to a cell element. The current collector also includes a member
extending out from the main body, the member being singularly folded
partially over the main body. An end of the member is configured to be
conductively coupled a terminal of the cell.

[0145] As utilized herein, the terms "approximately," "about,"
"substantially," and similar terms are intended to have a broad meaning
in harmony with the common and accepted usage by those of ordinary skill
in the art to which the subject matter of this disclosure pertains. It
should be understood by those of skill in the art who review this
disclosure that these terms are intended to allow a description of
certain features described and claimed without restricting the scope of
these features to the precise numerical ranges provided. Accordingly,
these terms should be interpreted as indicating that insubstantial or
inconsequential modifications or alterations of the subject matter
described and claimed are considered to be within the scope of the
invention as recited in the appended claims.

[0146] It should be noted that the term "exemplary" as used herein to
describe various embodiments is intended to indicate that such
embodiments are possible examples, representations, and/or illustrations
of possible embodiments (and such term is not intended to connote that
such embodiments are necessarily extraordinary or superlative examples).

[0147] The terms "coupled," "connected," and the like as used herein mean
the joining of two members directly or indirectly to one another. Such
joining may be stationary (e.g., permanent) or moveable (e.g., removable
or releasable). Such joining may be achieved with the two members or the
two members and any additional intermediate members being integrally
formed as a single unitary body with one another or with the two members
or the two members and any additional intermediate members being attached
to one another.

[0148] References herein to the positions of elements (e.g., "top,"
"bottom," "above," "below," etc.) are merely used to describe the
orientation of various elements in the FIGURES. It should be noted that
the orientation of various elements may differ according to other
exemplary embodiments, and that such variations are intended to be
encompassed by the present disclosure.

[0149] It is important to note that the construction and arrangement of
the current collectors for an electrochemical cell as shown in the
various exemplary embodiments is illustrative only. Although only a few
embodiments have been described in detail in this disclosure, those
skilled in the art who review this disclosure will readily appreciate
that many modifications are possible (e.g., variations in sizes,
dimensions, structures, shapes and proportions of the various elements,
values of parameters, mounting arrangements, use of materials, colors,
orientations, etc.) without materially departing from the novel teachings
and advantages of the subject matter described herein. For example,
elements shown as integrally formed may be constructed of multiple parts
or elements, the position of elements may be reversed or otherwise
varied, and the nature or number of discrete elements or positions may be
altered or varied. The order or sequence of any process or method steps
may be varied or re-sequenced according to alternative embodiments. Other
substitutions, modifications, changes and omissions may also be made in
the design, operating conditions and arrangement of the various exemplary
embodiments without departing from the scope of the present invention.